President Trump’s top national security adviser said Sunday that Russia should be pressed on whether it knew the Syrian regime would carry out a deadly chemical attack against civilians in a rebel-held area last week.

“I think what we should do is ask Russia, ‘How could it be, if you have advisers at that airfield, that you didn’t know that the Syrian air force was preparing and executing a mass murder attack with chemical weapons?’ ” H.R. McMaster said in a live morning interview on “Fox News Sunday.” “I think we ought to ask them that question.”

McMaster’s comment came ahead of a planned visit to Moscow by Secretary of State Rex Tillerson — a trip that has become exponentially more sensitive after Trump ordered missile strikes against a Syrian airfield on Thursday. Those strikes prompted a sharply critical response from the Kremlin, including a Facebook post from Prime Minister Dmitry Medvedev declaring that it has placed the United States “on the verge of a military clash with Russia.”

Russia has placed warplanes and air defense systems with associated troops in Syria since 2015 and has also deployed warships in the Mediterranean Sea off the Syrian coast in an open bid to prop up the regime of Syrian President Bashar al-Assad. The Kremlin blamed the chemical weapons attack on terrorists, not on Assad’s regime.

Speaking two television programs Sunday, Tillerson said that he had not seen any conclusive evidence that Russians were involved in carrying out the chemical weapons attack. But he dismissed the Russian explanation for the attack and said that the government of Russian President Vladimir V. Putin deserved blame for failing to live up to its role — rooted in a 2013 accord — in ensuring that chemical weapons were removed from Syria.

“We know from our own information and open-source information that their alternative explanation is simply not credible,” Tillerson said on CBS’s “Face the Nation” Sunday. “There’s little question as to who was responsible for these attacks: It was Bashar al-Assad. And I think the Russians need to think more carefully about the commitment they made under the chemical weapons agreements to be the guarantor that these weapons would be seized, they would be removed, they would be destroyed. … Clearly they have failed in their commitment to the international community.”

Tillerson said on ABC’s “This Week” that he would raise the U.S.’s concerns this week with Foreign Minister Sergey Lavrov: “I don’t draw conclusions of complicity at all, but clearly they’ve been incompetent and perhaps they’ve just simply been outmaneuvered by the Syrians.”

Nikki Haley, the U.S. ambassador to the United Nations, was even more sharply critical of Russia for continuing to deny Assad’s role in deploying chemical weapons in last week’s attack.

“When this chemical weapons murder happened to so many people, Russia’s reaction was not, ‘Oh, how horrible,’ or ‘How could they do this to innocent children,’ or ‘How awful is that?’ ” Haley said on NBC’s “Meet the Press” on Sunday. “Their initial reaction was, ‘Assad didn’t do it. The Syrian government didn’t do it.’

“The first priority for them was to cover for Assad,” she added.

McMaster said Sunday that the United States should “appeal rationally to Russia” and said that the U.S.-Russian relationship “can be whatever the Russians want it to be.”

“Do they want it to be a relationship of competition and potential conflict?” he continued. “I don’t see how that’s in Russian interests. Or do they want it to be a relationship in which we can find areas of cooperation that are in our mutual interest. How is it in anyone’s interest that this conflict in Syria and this catastrophe in the greater Middle East continues? They can be part of the solution or they can continue what has been a really a very sophisticated campaign of subversion against western interests and a campaign of subversion and intervention on behalf of a murderous regime in the Middle East. And so I think this is what our secretary of state will be exploring with the Russian leadership this week, and the president is determined to do everything he can to advance American interests.”

Abby Phillip contributed to this report.